Steering apparatus for an autogenous cutting torch

ABSTRACT

A steering apparatus for an autogenous cutting torch for cutting holes of desired shape in flat or curved sheet walls, such as in the wall of a pipe. The steering apparatus comprises a holder arm for an autogenous cutting torch and means for guiding the holder arm in a manner that the autogenous cutting torch can be run along a certain desired orbit or path. A problem with the prior art steering equipment is the limited scope of application, e.g. to the cutting of flat sheets only. In order to expand the scope of application to also cover curved surfaces as well as combinations of flat and curved surfaces, the holder arm is designed as a long rod (4), arranged to be axially displaceable on a slide guide (7). The steering movement of an autogenous cutting torch crosswise relative to holder arm (4) is arranged to be effected by means of steering elements (9, 10, 12, 19) engaging the holder arm at a distance from cutting torch (3) and turning said holder arm (4) around its longitudinal axis and/or displacing holder arm (4) in its transverse direction, on a slide guide which is perpendicular to said slide guide (7).

The present invention relates to a steering apparatus for an autogenouscutting torch for cutting a hole of desired shape in a wall, such as thewall of a pipe or a flat sheet, said steering apparatus comprising aholder arm for the autogenous cutting torch and means for steering theholder arm so as to guide the autogenous cutting torch along a certaindesired path.

Previously known is to autogenously cut out pieces of a desired templateshape from a flat sheet by employing a steering device, wherein amagnetic roller rolls along the edges of a template having desired shapewhile simultaneously carrying the holder arm of an autogenous cuttingtorch. A drawback of this steering device is that it is only capable ofcutting flat or planar sheets. However, there is a need to cut holes ofvarious sizes both in curved wall surfaces and in the combinations ofcurved and flat surfaces. One example of this is cutting of an oval holein the side of a pipe when the purpose is to form a collar for abranching joint by pulling the hole edges upwards. In this case, thehole to be cut must be oval longitudinally of the pipe in order to bringedges of the eventual collar essentially onto the same level. Anothernot eworthy example is cutting of check gates or manholes in the side ofcontainers of various shapes, whereby the wall to be cut can bepartially flat and partially, e.g. at its edges, curved. Heretofore,there has not been available a steering apparatus for an autogenouscutting torch, which would be suitable for cutting holes of desiredshapes both in flat and curved wall surfaces.

An object of the invention is to eliminate this drawback and, accordingto the invention, this has been accomplished by means of a surprisinglysimple design of a steering apparatus. A steering apparatus of theinvention is characterized in that the holder arm consists of anelongate holder bar mounted for axial displacement on a slide control,the motion of an autogenous cutting torch crosswise relative to theholder arm being effected by means of steering elements engaging theholder arm at a distance from the autogenous storch, said elementsrotating the holder arm around its longitudinal axis and/or displacingthe holder arm crosswise, supported by a slide control perpendicular tothe above-mentioned slide control.

The essence of a solution of the invention is thus the use of anelongate holder arm, said holder arm being selectively or as variouscombinations settable in (1) controlled axial movement, (2) rotatingmotion dependent on axial movement, and (3) movement perpendicular toaxial direction.

The invention will now be illustrated in more detail by means of workexamples with reference made to the accompanying drawings, in which

FIG. 1 is a perspective view of a steering apparatus for an autogenouscutting torch according to a first embodiment of the invention forcutting an oval hole in a pipe.

FIG. 1A shows an alternative mounting of an autogenous torch for cuttingan oval hole in the outer face of a pipe.

FIG. 2 shows a further developed embodiment capable of cutting both ovaland circular holes both in curved and flat walls.

FIG. 3 shows a detail of the steering apparatus as depicted in FIGS. 1and 2.

Referring to FIG. 1, a pipe P is to be provided with an oval hole 2 andsupported on a stand, not shown. The end of pipe P is placed against aback stop 1a extending from the body of a steering apparatus 1. Anautogenous cutting torch 3 is mounted on the end of a holder arm 4provided by an elongate rod, so that the radial distance of a torchnozzle from the axial extension of holder arm 4 is adjustable foradapting the apparatus to various pipe diameters.

FIG. 1 shows cutting of an oval hole in a pipe from the interior of thepipe. Thus, the autogenous cutting debris shall not remain inside thepipe. However, it is often preferable and, when dealing with smallpipes, for practical reasons necessary to effect the cutting from theexterior of a pipe. FIG. 1A shows an autogenous cutting torch 3 and itsmounting arrangement for this purpose. Thus, the end of arm 4 is fittedwith a radial distance or spacer element 4a to which is secured anauxiliary arm 4b, which is parallel to arm 4 and radially spaced fromthe extension of the axis of arm 4. The cutting torch 3 is mounted onthe end of arm 4b so that its torch nozzle will be at a desired distancefrom the extension of the axis of arm 4 directed towards said extensionof axis.

Holder arm 4 is journaled to frames 5 and 6 to be rotatable around itsaxis and axially displaceable. However, the axial displacement can belocked e.g. by means of a screw fitted in the inner rim of a bearing 8.Frames 5 and 6 are connected with each other by slide rods 7 which areaxially slideably supported on the body 1 by means of slide bearings 7a.

Frame 6 carries a transverse slide rod 9 which extends through a slidehole 11 in a slide element 10.

An assembly 12, provided by a gear wheel and an arm mounted thereon, isarranged to be rotated around a fixed vertical axle 13 by means of asmall gear 17 driven by a motor 15 through a reduction gear 16. The armof assembly 12 is articulated to slide element 10 by means of a pivot14. The arm of said rotatable assembly 12 is provided with holes 18 sothat the distance of pivot 14 from axle 13 can be selected. Instead ofthe stepped adjustment, it is naturally possible to use stepless slideadjustment in order to adjust the distance between axle 13 and pivot 14.

Holder arm 4 carries an intermediate element 19 through which arm 4 isdisplaceable and lockable in a desired position. Thus, the intermediateelement 19 and the inner rim of bearing 8 can be connected to each otherso that they both can be locked on arm 4 at the same time. Thecooperation between the intermediate element 19 and the slide element 10will be further described hereinbelow with reference made to FIG. 3.

As shown in FIG. 3, the intermediate element 19 is fitted with a leverarm 20 extending through an adjustment element 22. The adjustmentelement 22 can be locked at a desired level on pins 21 projecting fromthe slide element 10. The adjustment element 22 is provided with acylinder member 23 which is turnable around the longitudinal axis andthrough which the lever arm 20 is slideable.

Operation of the apparatus is explained in the following. The radialdistance of the nozzle of an autogenous cutting torch 3 from the axialextension of holder arm 4 is adjusted according to the diameter of pipeP, i.e. to be slightly less than the internal diameter of pipe P. In thesupport stand, pipe P is pushed so as to surround the autogenous cuttingtorch 3 and the end of its holder arm 4 until it engages the back stop1a. Holder arm 4 is displaced axially relative to frames 5 and 6 as wellas relative to the intermediate element 11 until a desired distance ofthe center of an eventual hole 2 from back stop 1a can be verfied from ameasuring scale 4a on holder arm 4. Thereafter, arm 4 is locked to beaxially immovable relative to frame 6 e.g. by means of a screw fitted inthe inner rim of bearing 8. Motor 15 is actuated whereby, while rotatingaround axle 13, said assembly 12 carries slide element 10 transverselyalong slide rod 9 and at the same time it carries slide rod 9 togetherwith its frame 6 and holder arm 4 in axial direction. The distancebetween axle 13 and pivot 14 determines the length of the major axis ofan oval hole 2. The level of adjustment element 22 determines theturning angle of arm 4 or the width of hole 2. While the nozzle of anautogenous cutting torch 3 travels along the desired oval path, thecutting flame is lit and the hole is run.

FIG. 2 shows a further development of the invention for cutting holesboth in curved and flat surfaces and also in combinations of flat andcurved surfaces. For this purpose, the sliding sleeves 7a of slide rods7 are mounted on a cradle 24 which is displaceable on slide guides 25 ina direction perpendicular to arm 4. If the movement of cradle 24 onslide rods 25 is locked, the operation complies with the caseillustrated in FIG. 1 and the apparatus can be used, as explained, towork an oval hole in the wall of a pipe P. However, if cradle 24 isreleased to travel on slide rods 25 and, in addition to this, themovement of slide element 10 on slide guide 9 is locked, it is possibleto make circular holes in a flat sheet. The operating characteristics ofthe apparatus will be particularly versatile due to the fact that slideelement 10 on frame 6 can be replaced by a fixed template whose outlinecorresponds to that of the hole to be cut. Gear 17 is replaced by amagnetic roller, said template running around the roller while thelatter rotates in its fixed position.

Thus, the embodiment shown in FIG. 2 can be used to cut circular holesin a flat sheet without a template, e.g. for making annular flanges and,by means of a template, shaped pieces of a desired pattern or outline.Thus it is preferable that removal of the pieces from the sheet can beeffected without moving the latter. For this purpose, the transverseslide guides 25 are mounted on a cradle unit 26 supported on atransverse slide guide unit 28 which, in effect, provides the actualfixed body for the apparatus. During the intervals between the cuttingoperations, said cradle unit 26 in arranged to move along the slideguide unit 28 e.g. over a hole distance 29, which corresponds to thedistance between the pieces to be cut off the sheet.

I claim:
 1. A steering apparatus for an autogenous cutting torch forcutting a hole of desired shape in a wall, such as in the wall of a pipeor in a flat sheet, said steering apparatus comprising a holder arm foran autogenous cutting torch (3) and means for steering the holder arm soas to guide the autogenous cutting torch along a determined orbit,characterized in that the holder arm comprises an elongated holder rod(4), arranged for axial displacement on a slide guide (7), and that themovement of an autogenous cutting torch crosswise relative to holder arm(4) is arranged to be effected by means of control elements engagingsaid holder arm at a distance from the cutting torch (3), said elementsturning the holder arm (4) around its longitudinal axis and/or displacesaid holder arm (4) in its transverse direction on a slide guide (25)perpendicular relative to said slide guide (7).
 2. A steering apparatusfor an autogenous cutting torch as set forth in claim 1, characterizedin that the control elements, rotating holder arm (4) around itslongitudinal axis and displacing it in axial direction, comprise anassembly (12) rotatable around a fixed vertical axle (13) and a slideelement (10) displaceable along a transverse slide guide (9), saidrotatable assembly (12) and slide element (10) being journaled (14) toeach other in a manner that, while the former (12) rotates, the latter(10) travels back and forth on its slide guide (9) and simultaneouslymoves said slide guide (9) back and forth in axial direction of holderarm (4), said slide guide (9) being lockable on holder arm (4) so as tobe axially immovable, and that to holder arm (4) is secured anintermediate element (19, 20) which is in engagement with slide element(10).
 3. A steering apparatus as set forth in claim 2, characterized inthat the slide guide (9) of said slide element (10) is mounted on aframe (6) to which the slide rods (7) for the axial slide steering ofholder arm (4) are secured and to which holder arm (4) is rotatablyjournaled.
 4. A steering apparatus as set forth in claim 3,characterized in that said holder arm (4) carries a measuring scale (4a)selected in a manner that the position of said intermediate element (19)or frame (6) on the measuring scale determines the distance of thecenter of an eventual hole (2) from the back stop (1a) of a work piece.5. A steering apparatus as set forth in claim 3, characterized in thatthe frame (6), which is mounted on holder arm (4), is fitted with atemplate which corresponds to the shape to be cut and whose edge isarranged to follow a rotatable, immovable magnetic roller.
 6. A steeringapparatus as set forth in claim 3, characterized in that said slideelement (10) is provided with a vertically displaceable, at variouslevels lockable adjustment element (22) by means of which it is possibleto adjust the length of the lever arm (20) of an intermediate element(19) mounted on the holder arm, whereby the same transverse travellingdistance of slide element (10) leads to a different turning angle ofholder arm (4).
 7. A steering apparatus as set forth in claim 3,characterized in that a pivot (14) between said rotatable assembly (12)and slide element (10) can be set at various distances (18) from therotating axis (13) of said rotatable assembly (12).
 8. A steeringapparatus as set forth in claim 1, characterized in that the radialdistance of a torch nozzle from the axial extension of holder arm (4) isadjustable.
 9. A steering apparatus as set forth in claim 2,characterized in that slide element (10) can be locked immovably onslide guide (9).
 10. A steering apparatus as set forth in claim 1,comprising a slide guide (25) perpendicular to the axial direction ofholder arm (4), characterized in that said perpendicular slide guide(25) is lockable.
 11. A steering apparatus as set forth in claim 1,characterized in that said torch nozzle (3) is mounted at a distancefrom the axial extension of holder arm (4) in a manner that it isdirected towards this axial extension (FIG. 1A).